Heat dissipation device having centrifugal fan

ABSTRACT

A heat dissipation device includes a centrifugal fan, a fan duct and a fin assembly. The centrifugal fan has an air outlet. The fan duct is fixed to the air outlet. The fan duct includes a plurality of guiding plates spaced from each other. A channel is defined between every two neighboring guiding plates. Each of the guiding plates includes a near end near the air outlet and a far end opposite to the near end away from the air outlet. The widths of the channels at the near ends are larger comparing to the portions of the air outlet when having smaller quantity of airflow, and are smaller comparing to the portions of the air outlet when having large quantity of airflow. Widths of the channels at the far ends are equal to each other. The fin assembly is positioned at the far ends of the guiding plates.

BACKGROUND

1. Technical Field

The present disclosure relates to heat dissipation devices, and particularly to a heat dissipation device incorporating a centrifugal fan.

2. Description of Related Art

Heat dissipation devices are often utilized to dissipate heat from heat generating electronic components, such as central processor units (CPUs). A typical heat dissipation device includes a fin assembly thermally connected with a heat generating component, and a blower for cooling the fin assembly. The blower includes a housing, and an impeller received in the housing. The housing defines an air outlet at one side thereof. The fin assembly is located at the air outlet.

During operation of the heat dissipation device, the fin assembly absorbs heat from the heat generating component. The impeller of the blower rotates and drives air to the fin assembly to evacuate heat from the fin assembly to the ambient environment. However, a large quantity of air flows to one side of the air outlet, whereas less air flows to an other side of the air outlet opposite to the one side. Thus, the blower does not fully optimize cooling of a portion of the fin assembly that is located at the other side of the air outlet. In addition, uneven distribution of the airflow at the air outlet can generate a plurality of vortexes at the center of the air outlet, which is a disadvantage for heat dissipation.

What is needed therefore is a heat dissipation device which can overcome the above mentioned limitations.

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the present embodiments can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present embodiments. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the views.

FIG. 1 is an isometric, assembled view of a heat dissipation device in accordance with an embodiment of the present disclosure, the heat dissipation device including a centrifugal fan, a fan duct and a fin assembly.

FIG. 2 is an isometric, exploded view of the centrifugal fan and the fan duct of FIG. 1.

FIG. 3 is an inverted view of FIG. 2.

FIG. 4 is a top plan view of the heat dissipation device of FIG. 1.

DETAILED DESCRIPTION

As shown in FIG. 1, the heat dissipation device 100 provided by an embodiment of the present disclosure is used for dissipating heat of electronic elements in an electronic device (not shown) such as a computer. The heat dissipation device 100 comprises a centrifugal fan 10, a fan duct 20 located at a lateral side of the centrifugal fan 10, and a fin assembly 30 fixed to the fan duct 20.

Also referring to FIGS. 2 and 3, the centrifugal fan 10 comprises a housing 11 and an impeller 14 rotatably received in the housing 11. The housing 11 comprises a plate-shaped top cover 111, a plate-shaped bottom cover 112 and a volute-shaped side wall 113 connecting the top and bottom covers 111, 112. The side wall 113 extends downwards from an outer periphery of the top cover 111 and is integrally formed with the top cover 111. A receiving room 15 is defined by the top and bottom covers 111, 112 and the side wall 113 for receiving the impeller 14. A circular air inlet 12 is defined in a center of the bottom cover 112. The side wall 113 comprises an arc-shaped main wall 1131 and a first auxiliary wall 1132 and a second auxiliary wall 1133 extending from two ends of the main wall 1131, respectively. The first and second auxiliary walls 1131, 1132 are configured to be plate shape and parallel to each other, to define a substantially rectangular air outlet 13 therebetween. During operation of the centrifugal fan 10, cooling air flows in the housing 11 through the air inlet 12, and is driven out through the air outlet 13 via the rotation of the impeller 14. The strength of the airflow at the air outlet 13 decreases from one side of the air outlet 13 to another side thereof. In the present embodiment, the impeller 14 rotates clockwise as shown in FIG. 4 and the strength of the airflow at the air outlet 13 decreases from the second auxiliary wall 1133 to the first auxiliary wall 1132.

The fan duct 20 is fixed at the air outlet 13 of the centrifugal fan 10. The fan duct 20 comprises a guiding portion 21, a securing portion 22 and a positioning portion 23.

The guiding portion 21 comprises a connecting plate 211 and a plurality of guiding plates 212 positioned on the connecting plate 211. The connecting plate 211 has a substantially trapezoid configuration and comprises a first end 2111 and a second end 2112 which is longer compared with the first end 2111. The width of the connecting plate 211 increases gradually from the first end 2111 to the second end 2112. The length of the first end 2111 is substantially equal to the width of the air outlet 13. The first end 2111 is in contact with the bottom cover 112. The guiding plates 212 extend upwardly and perpendicularly from a top surface of the connecting plate 211. Heights of the guiding plates 212 are substantially equal to that of the air outlet 13. The guiding plates 212 are bent along a direction from the first end 2111 of the connecting plate 211 to the second end 2112. Each of the guiding plates 212 comprises a near end 2121 near the air outlet 13 and flush with the first end 2111 of the connecting plate 211, and a far end 2122 away from the air outlet 13 and opposite to the near end 2121. The guiding plates 212 are spaced from each other and a channel 215 is defined between every two neighboring guiding plates 212. A space between every two neighboring guiding plates 212 at the near ends 2121 gradually increases from the one side of the air outlet 13 to the another side. A space between every two neighboring guiding plates 212 at the far end 2122 substantially stays as a constant. In other words, the widths of the channels 215 at the near ends 2121 gradually increase from the one side of the air outlet 13 to the another side, and the widths of the channels 215 at the far ends 2122 are equal to each other. In this embodiment, the number of the guiding plates 212 is five. Two outermost guiding plates 212 extend respectively from two lateral sides of the connecting plate 211, and the near ends 2121 of the two outermost guiding plates 212 respectively abut against an outer side of the first auxiliary wall 1132 and an outer side of the second auxiliary wall 1133. The widths of the channels 215 at the near ends 2121 of the guiding plates 212 increase from the second auxiliary wall 1133 to the first auxiliary wall 1132. The ratio of the widths of the channels 215 at the near ends 2121 of the guiding plates 212 along a direction from the second auxiliary wall 1133 to the first auxiliary wall 1132 is 1:1.5:2:4.

Also referring to FIG. 4, the securing portion 22 comprises two securing plates 221, and a locking plate 222 and an auxiliary plate 223 extending from one of the securing plates 221 by connecting with the locking plate 222. Each securing plate 221 extends outwardly and horizontally from a top of one of the outermost guiding plates 212. A securing hole 225 is defined in each securing plate 221 for a fastener such as a screw to be inserted through to secure the fan duct 20. The locking plate 222 extends downwardly from an outer edge of the securing plate 221. The auxiliary plate 223 extends outwardly and horizontally from a bottom edge of the locking plate 222. The auxiliary plate 223 and the connecting plate 211 are in substantially the same horizontal plane. Securing holes (shown in FIG. 3, not labeled) are defined in the auxiliary plate 223 and the connecting plate 211 for the fasteners inserting through to secure the fan duct 20 on a shell (not shown) of an electronic device in which the heat dissipation device 100 is accommodated.

The positioning portion 23 comprises two positioning plates 231 respectively extending rearwards from the far ends 2122 of the two outermost guiding plates 212, and two supporting plates 232 respectively extending inwardly and horizontally from the tops of the two positioning plates 231. The positioning plates 231 are substantially parallel to each other. A substantially quadrate receiving space 233 is defined by the positioning plates 231 and the supporting plates 232 for receiving the fin assembly 30.

The fin assembly 30 comprises a plurality of plated fins 31 assembled together. A passage 32 is defined between every two neighboring fins 31. The fin assembly 30 is received in the receiving space 233 of the fan duct 20. The passages 32 are communicated with the channels 215 of the guiding portion 21.

The widths of the channels 215 at the near ends 2121 are configured to increase along the direction from the second auxiliary wall 1133 to the first auxiliary wall 1132 in contrast to the strength of the airflow at the air outlet 13 that increases along the direction from the first auxiliary wall 1132 to the second auxiliary wall 1133. Thus, the quantity of the airflow entering into the channels 215 is adjusted to be substantially equal to each other. Further, the airflow out of the channels 215 are evenly diffused onto the fin assembly 30 due to the widths of the channels 215 at the far ends 2122 being substantially equal to each other. Benefitting from the adequately exploiting of the airflow, the heat from the fin assembly 30 can be dissipated more evenly, whereby the heat dissipation efficiency of the heat dissipation device is enhanced.

It is noted that the guiding portion 21 of the fan duct 20 can be positioned in the air outlet 13 of the centrifugal fan 10. When the guiding portion 21 is positioned in the air outlet 13, the connecting plate 211 can be omitted, and the guiding plates 212 can be directly positioned between the top and bottom covers 111, 112 of the centrifugal fan 10. In addition, the principle for setting the widths of the channels 215 at the near ends 2121 is in accordance to the amount of the airflow required or desired at the air outlet 13, which means that the width of the channel 215 at the near end 2121 is relatively large in comparison to the portion of the air outlet 13 when the amount of desired airflow being relatively small, and is relatively small in comparison to the portion of the air outlet 13 when the amount of the airflow being relatively large.

It is believed that the present embodiments and their advantages will be understood from the foregoing description, and it will be apparent that various changes may be made thereto without departing from the spirit and scope of the disclosure or sacrificing all of its material advantages, the examples hereinbefore described merely being preferred or exemplary embodiments of the disclosure. 

1. A heat dissipation device comprising: a centrifugal fan having an air outlet, a plurality of quantities of airflow generated from the centrifugal fan being different at a plurality of different portions of the air outlet; a fan duct fixed to the air outlet of the centrifugal fan, the fan duct comprising a plurality of guiding plates spaced from each other, a channel being defined between every two neighboring guiding plates, each of the guiding plates comprising a near end near the air outlet and a far end opposite to the near end and away from the air outlet, the widths of the channels at the near ends being larger in comparison to the portions of the air outlet when having smaller quantity of airflow, and being smaller in comparison to the portions of the air outlet when having larger quantity of airflow, and the widths of the channels at the far ends being equal to each other; and a fin assembly positioned at the far ends of the guiding plates.
 2. The electronic device of claim 1, wherein the quantity of airflow decreases from one side of the air outlet to an another side of the air outlet, and the widths of the channels at the near ends increase from the one side of the air outlet to the another side of the air outlet.
 3. The heat dissipation device of claim 2, wherein the quantity of the guiding plates is five, and the ratio of the widths of the channels at the near ends along a direction from the one side to the another side of the air outlet is 1:1.5:2:4.
 4. The heat dissipation device of claim 1, wherein the fin assembly comprises a plurality of fins, the fins having a plurality of passages defined therebetween, and the passages being communicated with the channels.
 5. The heat dissipation device of claim 1, wherein the fan duct further comprises a connecting plate on which the guiding plates are extended, the connecting plate comprising a first end near the air outlet and a second end opposite to the first end, the length of the first end being substantially equal to the width of the air outlet, the second end being longer than the first end, and the each of the guiding plates being bent along a direction from the first end to the second end.
 6. The heat dissipation device of claim 1, wherein the fan duct further comprises two positioning plates respectively extending rearwards from two outermost guiding plates, and two supporting plates respectively extending inwardly from the two positioning plates, and a receiving space being defined by the positioning plates and the supporting plates for receiving the fin assembly.
 7. The heat dissipation device of claim 1, wherein heights of the guiding plates are equal to that of the air outlet.
 8. A centrifugal fan comprising: a housing defining a receiving room, an air inlet and an air outlet therein; an impeller rotatably received in the receiving room, an airflow entering through the air inlet and driven by the impeller to expel air outside of the receiving room through the air outlet, the strength of the airflow being different at a plurality of different portions of the air outlet; and a plurality of guiding plates fixed at the air outlet and spaced from each other, a channel being defined between every two neighboring guiding plates, each of the guiding plates comprising a near end near the air outlet and a far end away from the air outlet, the widths of the channels at the near ends being larger in comparison to the portions of the air outlet when having smaller quantity of airflow, and being smaller in comparison to the portions of the air outlet when having larger quantity of airflow, and the widths of the channels at the far ends being equal to each other.
 9. The centrifugal fan of claim 8, wherein the housing comprises a top cover, a bottom cover, a first auxiliary wall and a second auxiliary wall positioned between the top and bottom covers, the air outlet being enclosed by the top and bottom covers, the first and second auxiliary walls, the strength of the airflow increasing from the first auxiliary wall to the second auxiliary wall, and the widths of the channels at the near ends increase from the second auxiliary wall to the first auxiliary wall.
 10. The centrifugal fan of claim 9, wherein the quantity of the guiding plates is five, and the ratio of the widths of the channels at the near ends along a direction from the second auxiliary wall to the first auxiliary wall is 1:1.5:2:4.
 11. The centrifugal fan of claim 9 further comprising a connecting plate positioned at a same horizontal plane with the bottom cover, and the guiding plates extending upwardly from the connecting plate.
 12. The centrifugal fan of claim 11, wherein the connecting plate comprises a first end in contact with the bottom cover and a second end opposite to the first end, the width of the connecting plate increasing from the first end to the second end, and the guiding plates bending along a direction along the first end to the second end.
 13. The centrifugal fan of claim 11, wherein the guiding plates are of the same height as the air outlet, and two outermost guiding plates are abutting against the first and second auxiliary walls, respectively.
 14. The centrifugal fan of claim 13, wherein the two outermost guiding plates extend rearwards to form two positioning plates, a supporting plate extending horizontally from the positioning plates, the positioning and supporting plates enclosing to define a receiving space adapted for receiving a fin assembly.
 15. The centrifugal fan of claim 13, wherein a securing plate extends outwardly from a top of one of the two outermost guiding plates, a locking plate extending downwardly from the securing plate, and an auxiliary plate extending outwardly and horizontally from the locking plate, the auxiliary plate and the connecting plate being at a same horizontal plane and defining a plurality of securing holes therein for securing the centrifugal fan. 